In recent years, fiber laser devices are used in machines for machining utilizing laser light and in medical devices such as a surgical knife utilizing laser light. A fiber laser device is a device in which laser light and pumping light emitted by a laser oscillator are input to an amplification optical fiber and amplified laser light is output from an output section.
In such a fiber laser device, a certain period of time is required from a point when the fiber laser device starts outputting the laser light until the intensity of the laser light is stabilized. In other words, a certain period of time is required for the laser light to rise.
The work efficiency is higher as the rise time of the laser light is shorter. Patent Document 1 listed below discloses such a fiber laser device that is stated to achieve a short period until the intensity of laser light is stabilized.
In the fiber laser device disclosed in Patent Document 1, constant low-intensity pumping light is input to an amplification optical fiber during a period (standby state period) before laser light is output from the fiber laser device to pump rare earth elements doped in the amplification optical fiber. Subsequently, seed laser light and high-intensity pumping light are input to the amplification optical fiber at the time when the laser light is output from the fiber laser device, the seed laser light is amplified and the amplified laser light is output. It is stated that the rise time of the laser light output from the fiber laser device is short since the rare earth elements of the amplification optical fiber are pumped in advance in this manner when the laser light is output from the fiber laser device (Patent Document 1).